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A STUDY OF THE RECOVERY OF 
 ALUMINA FROM A CLAY 
 
 BY 
 
 GEORGE FERRIS WATSON 
 
 THESIS 
 
 FOR THE 
 
 DEGREE OF BAGHELOROF SCIENCE 
 
 IN 
 
 CHEMISTRY 
 
 COLLEGE OF LIBERAL ARTS AND SCIENCES 
 
 UNIVERSITY OF' ILLINOIS 
 
 1922 
 
5 
 
 UNIVERSITY OF ILLINOIS 
 
 __Augus_t__4___ _I92_3._ 
 
 THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY 
 
 G eo rge_ F 1 er ris _ Wats on 
 
 ENTITLED A__Stjudy_ _o f_ _t h_e_ Re cj? verv_ _of_ .Alumina. Fr om_ _Q1 ay 
 
 IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE 
 degree of _ _ B a c_h elo r _ of _ _S c i_3 no e_ _i n _ C_h e m is t ry 
 
 
 X 
 
 7 
 
 * rt : > 
 
Digitized by the Internet Archive 
 in 2015 
 
 https://archive.org/details/studyofrecoveryoOOwats 
 
I wish to sincerely thank Prof. S. W. Parr and Dr. W. S 
 Putman for the help they have given me on this problem and 
 in preparing this thesis. 
 

 
 
 
 
 
 
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TABLE OF CONTENTS 
 
 page 
 
 1. INTRODUCTION I 
 
 2. HISTORICAL 4 
 
 3. THEORETICAL 8 
 
 4. EXPERIMENTAL II 
 
 (a) The Sample 
 
 (b) The Analysis 
 
 (c) Decomposition by acids and alkali 
 
 5. DISCUSSION OF RESULTS 14 
 
 6. SUMMARY 16 
 
 7. BIBLIOGRAPHY 17 
 

1 . 
 
 A STUDY OF THE RECOVERY OF ALUMINA FROM A CLAY. 
 
 I. INTRODUCTION 
 
 The use of metals in modern times has reached unprecedented 
 heights. Our transportation, buildings, life, prosperity, and 
 civilization directly depend upon its production. The metallurgy 
 of iron has been known and made use of for ages. The ancients 
 were familiar with the uses of brasse and bronzes. But the main 
 demand has fallen upon iron on account of its occurence, known 
 metallurgy, desirable qualities, and many alloys. The oxides of 
 iron compose approximatly five per cent of the earths crust. 
 Thousands of chemists and Technical men have devoted their time 
 to the determination of the properties, metallurgy, alloys and 
 possibilities of the metal. And the problems are ever more com- 
 plex and daily more is discovered as to the characters of the 
 metal and its alloys. 
 
 It was not until comparatively recent times that the world 
 has been concerned with the rise in importance of a new metal 
 which we know as aluminum. Aluminum occurrs in the ground as a 
 clay or a bauxite in which it is associated with the elements 
 silicon, oxygen, alkali earths, iron, sodium and a few of the 
 common metals. The compounds of aluminum are very important 
 when we realize that they make up eight per cent of the earths 
 crust. Bo that it is very evident that aluminum is every bit as 
 important as iron. 
 
 At the present time the manufacture of aluminum is dependent 
 upon the supply of the mineral bauxite. This mineral is a com- 
 bination of deaspore (Al.9O3.3H2 ) and brown hematite ( FE 2 0 3 . 
 
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 3H..0.) In the United States bauxitehas been mined since about 
 1335, and this supply has been taken from four states, Alabama, 
 Georgia, Tennessee, and Arkansas. 'The following table shows 
 the production of Bauxite by states in the United States 
 Table --I. * 
 
 Production of bauxite in the United States 
 
 Alabama)- 27,409 -25, 003 -62, 164 -43, 076 -40,029 
 
 Georgia) 
 
 Tenn. ) -132, 332 -272, 022 -506, 556 -333,490 -431,279. 
 
 Arkansas ) 
 
 There were no figures available on the estimated reserves of the 
 supply, but it is safe to conclude that these deposits are cer- 
 tainly only a very small percentage of the total U. S. supply. 
 
 It is regrettable that a metal of such wide occurence and such 
 valuable properties is obliged to owe its existence to a mineral 
 of such comparatively narrow resources. Also in order for a 
 bauxitic mineral to be of use commercially it must have at least 
 fifty percent of alumina and a low percentage of silica and other 
 impurities. These narrow specifications upon the production of 
 aluminum will in years to come hinder the use of the metal con- 
 si derably . 
 
 The production of aluminum in commercial quantities given 
 rise to a thousand and one uses. On account of its extreme 
 lightness it has found a ready use in many fields, especially 
 small articles as keyes, vi sting cards, thimbles, cigarette cases, 
 etc. Its use in cooking utensils is known every where on ac- 
 count of its conductivity and resistance to acids. It has been 
 especially valuable in military equipment for its lightness, 
 resistance to oxidation, and strength. Its lightness was also 
 

 
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appreciated in the automobile andaeroplane, and a great field 
 was opened up there. And it is now a fact that aluminum more 
 than holds its own with nickle, copper, brass, and even iron. 
 And even with its many uses very little is known concerning 
 its alloying and most economic metallurgy. 
 

 
 
 
 
 
 
 
 
 
 
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4. 
 
 1 1. HI STORY 
 
 Aluminum is essentially a modern metal. The first reference to 
 such a metal was not until 1760 when Morveau, in Prance, calcined 
 an alum and called the resulting product alumina. Lavoisier first 
 suspected the existence of a metallic base of earths, and he sus- 
 pected alumina of being an oxide of a metal which was called 
 aluminum. 
 
 The first attempts at the production of pure aluminum was 
 started in 1007, and the general process was the reduction by 
 an alkali metal. Due to the meagre knowledge of electricity and 
 electrical apparatus the decomposition by this method was never 
 studied closely, although Davy did try this method. Wohler was 
 the first to isolate aluminum and he accomplished this by decom- 
 position of aluminum cloride with potassium. But he got a fine 
 gray powder which could not be used for the determination of the 
 properties of the metal. Later in 1845, Wholer got the metalic 
 form by passing potassium va ors over aluminum cloride in boats, 
 ^rom globules obtained here the properties of the metal were de- 
 termined. 
 
 The main work upon aluminum was left to H. St. Claire Deville, 
 who devoted his life to the study of Aluminum. In 1845 Deville, 
 although ignorant of Wohler's work, passed aluminum cloride over 
 potassium and instead of getting the aluminum proto-clori de he 
 obtained the pure metal. Recognizing the importance of his work 
 the Acd. of Sciences donated two thousand francs for the contin- 
 uance of his work. His first attempts were the decomposition by 
 the use of a battery, but this method was not successful so he 
 turned to the use of sodium as a reducing agent. By this means 
 

 
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 a quanity of the metal was prepared, after which Napoleon III. gave 
 him permission to continue his work at the Emperor's expence. By 
 thiB method Deville was given ample funds to pursue his research 
 and he was aided at this time by two young chemists, Chas. and Alex 
 Tissier. These two afterwards left Deville and ipened up plants 
 of their own. Deville operated plants by which aluminum was re- 
 duced by sodium and these plants started in France ran for a num- 
 ber of years and turned out a quanity of the pure metal. 
 
 From this time on the principle endeavors were chiefly 
 toward perfecting the process and reducing the price of the metal. 
 In 1832 a Company was started in England for the preparation by 
 the usual method and a product of reasonable purity was obtained. 
 
 At this time came the wonderful invention of H. Y. Castner of New 
 York on tne production of sodium. This invention reduced the price 
 of sodium by seventy five per cent. Mr. Webster of the plant in 
 England induced Mr. Castner to open up a plant in England in which 
 both processes were imployed. This plant was built in 1883 and 
 turned out 100,000 pounds of aluminum annually. The following 
 table gives an indication of the price tend of aluminum. 
 
 Table II 2 
 
 Price of Aluminum 
 
 1854 1855 1856 1857 1853 1859 1878 1890 1891 1895 
 
 ^/lb. 
 
 on cont. 259.2 103.50 32.9 25.92 17.33 11.34 2.98 1.30 0.32 
 
 The first commercial attempts were about 1885 toward elec- 
 trical decomposition. Of these processes which were patented at 
 that time, those of Cowles, Herault, and Hall stand forth. Chas. 
 k. Hall of Oberlin Ohio prepared a bath of fused cryolite with the 
 al um ina dissolved in it. An electric current was used to precipi- 
 

 
 
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 tate the pure aluminum. This process was the wonder of the times 
 as it reduced aluminum to a commercial price with maximum of purity. 
 This process has been the outstanding one wvery since that time 
 and it seems to be the main one for many years to come. 
 
 The difficult thing now is the preparation of the pure alum- 
 ina. In the early days of aluminum production the preparation of 
 the alumina was tather simple. In a large number of cases the 
 mineral cryolite (AlgS’gSUaF ) was used. Alumina was also prepared 
 by the ignition of ammonium alum or an alum free from iron. Bauxite 
 was also used and alumina prepared by the fusion with sodium car- 
 bonate and formation of sodium alurainate. This alurainate was then 
 extracted with water and filtered. Carbon dioxide was then passed 
 through the clear solution and aluminum hydrate formed. This hyd- 
 rate was then filtered, sodium carbonate regenerated, and the 
 hydrate calcined to alumina. But at the present time alumina is 
 prepared exclusively by the M BAeyer pro cess M . In this process the 
 ore is ground fairly fine, kilned to destroy the organic matter, 
 and mixed with a solution of caustic soda to a sp.gr. of 1.45 at 
 a pressure of seventy pounds per sq. inch for eight hours. The 
 mass is then blown into a tank by its own pressure and water added 
 to a spec. grav. of 1.25 so as not to ruin the asbestos filter which 
 removes the hydrates of iron and silica. The sodium hydrate is 
 agitated with alumina for thirty six hours when approximatly seven- 
 ty per cent of the alumina in the solution will be precipitated. 
 
 The Alumina is then filtered, washed, and partially dried. The 
 filtarte is then concentrated to 1.45 and used for another batch of 
 solution. The precipitate is finally calcined at 1000 degrees to 
 insure proper crystalline form. 
 

 
 
 
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 The mystery, romance and financial promise of aluminum have 
 attrached chemists and technical men from all the world. Enorm- 
 ous amounts of work have been done upon the manufacture of the 
 metal. But it is readily seen that the amount of work yet to be 
 done is stupendous. The results of these men are shown in the 
 numerous patents in the Capitals of the various nations. But 
 these processes have not brought forth any startling advances. The 
 various methods for the purification of the alumina all follow the 
 same principles; a reduction with an alkali or an alkali earth; a 
 replacement by an active gas as a halogen or carbon dioxide; or a 
 pure solution with a strong solvent. 
 

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3 . 
 
 Ill THEORETICAL 
 
 The preparation of alumina for the manufacture of aluminum 
 must be a true commercial and economic process. The old time 
 processes of fusion with sodium carbonate or ignition of an alum 
 can not be considered for several reasons. Pirst is the limited 
 supply of the mineral with which they are concerned; second the 
 obious cost of materials and the waste which they produce. At 
 the present time we are preparing alumina by the Baeyer process 
 which I have previously describe in the Historical section. This 
 is a good method an economical one if we have a large supply of 
 the proper mineral to work with. In order for this process to be 
 commercial the alumina content must be above fifty per cent, the 
 Siog content below 15 percent, and the Fe£03 and Sio2 con ‘t® n 't 
 correspondingly low. How this imposes narrow specifications 
 upon the use of this process as today only certain bauxites are 
 used. It is necessary that this process be improved, a larger 
 supply of the mineral opened up, or a new process developed. 
 
 In looking up the literature upon this subject we are 
 surprised with the scores of patents issued for the manufacture 
 and purification of alumina. But when we study these we find 
 that they all simmer down to really a few which hold the gen- 
 eral principles for them all. So we will here mention a few 
 showing what is being done in the line of new processes. 
 
 We find a number of the new processes depending upon the 
 solvent action of some acid or alkali. United States Patent I, 
 301,394 was issued for the decomposition of aluminous ores with 
 sulphuric acid. The aluminum dissolved was converted into the 
 alum by the addition of potassium sulphate. Then the alumina was 
 

 
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prepared by ignition and the K 2 SO 4 was regenerated. How this pro- 
 cess makes it necessary that the aluminum material present be sol- f 
 uble in sulphuric acid. And it is a fact that only a small por- 
 tion of our aluminous ores have the aluminum held in a sulphuric 
 acid soluble condition. 
 
 Reduction processes have been rather popular since the 
 discovery of aluminum. Mr. H. A. Richmond has developed a process 
 along these lines. This process consisted in mixing kaolin, 
 pyrites, and carbon in the proportions of 132,120,21. This mixture 
 was heated in an electric furnace to a high temperature where the 
 alumina formed as a molten layer on top of the molten iron. 
 
 Carbon monoxide and SiS 2 are given off as a gas. Where sulphur 
 is used instead of the pyrites the alumina was practically pure. 
 
 The process is valuable as it takes care of the iron present in 
 the ore which is always a very troublesome element. This process 
 seems to be of considerable value especially when the time comes 
 for the removal of aluminum from blast furnace slags. 
 
 A process very similar to the "Baeyer Process" was developed 
 by B. J. Halvorsen and issued in U. S. patent I, 333, 020. ® This 
 consisted in treating labradorite with ammonia in an auto clave 
 at a pressure of from ten to fifteen atmospheres, for eight hours. 
 This is then removed by decatation and filtration and heated to 
 150 degress. Thus the alumina is formed, the ammonia is regenerated 
 
 Louis-Gabriel Patrouilleau worked upon a silica aluminous ore 
 which was very nearly free from iron. He heated the ore to a 
 dark residue and then passed clorine gas thru it. This gave the 
 
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 clo rides of silica and aluminum. The Si cl 4 was decomposed with 
 water and the H 2 Si 04 was separated. The hydro clo ric acid was 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 expelled upon evaporation. Thio process has the obvious diffi- 
 culty that it must be free from iron when in reality it is very 
 hard to obtain an aluminous ore which does not contain more or 
 less iron. 
 
 An unusual process is that of E. E. Dutt in which ASgOg is 
 used instead of the So2« Olay is acted upon at a red heat by the 
 oxide in the presence of calcium cloride. The calcium aluminate 
 formed is treated with aluminum cloride and water and the result 
 ing product is the aluminum hydroxide. This aluminum hydroxide 
 is then calcined to alumina. This process seems to have some 
 promise to it but for economical reasons it would probably run 
 into difficulties. 
 
 So that in examining a clay or a mineral as to its poss- 
 ibilities in the aluminum industry there are no precedents to 
 follow. Each investigar has a problem of his own depending upon 
 the ore used. 
 

 
 
 
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 IV EXPERIMENTAL 
 
 The samples of the material used in this work were obtained 
 from Dr. Parmelee 8 of the Dept, of Ceramics of the University of 
 Illinois. The samples were obtained by that department from de- 
 posits in the state of Missouri which are situated along the C. R. 
 I. & P. railroad in the counties of Pranklin, Gasconade, and 
 Maries. These deposits have been worked fro some time and. the 
 product used for the manufacture of abrasives and of refractories. 
 There were no figures available as to the possible extent of the 
 deposits but they have long been looked upon as a possibility in 
 the manufacture of aluminum. The clay is a rough, sandy looking 
 material with a yellowish or somewhat reddy appearance. The clay 
 is of a diaspore composition. 
 
 The analysis of this material was made by a sodium carbonate 
 fusion in a platinum crucible. By this means everything went into 
 solution. The fusion was carried out in the ordinary way and re- 
 sulting material was dissolved in HLC and evaporated to dryness. 
 
 It was then taken up with water and again evaporated to dryness. 
 The residue was taken up with water and the J^SiC^ had impurities 
 of aluminum hydroxide so the silica was dissolved in HP and the 
 residue ignited and weighed. This loss in weight gave the correct 
 amount of silica in the sample. The aluminum present in the sam- 
 ple was precipitated with NH^OH and NH^Cl, filtered, ignited and 
 weighed. The Pe present in the aluminum was dissolved out with 
 HCh and Lc titrated with standard Kuno^. The loss in weight of the 
 aluminum gave the correct amount of aluminum present. The calcium 
 
 and barium were precipitated from the aluminum hydroxude filtrate 
 by (NH 4 )2 c 2°4 and filtered ignited and weighed. The following 
 table _gj .v_eB t h e,.„analyji.^-. 
 

 
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Table III 
 
 12 
 
 Analysis of Missouri Olay 
 
 Moisture — 0.33$ 
 
 Si0 2 — — 11.70 $ 
 
 Alumina 
 Calcium (CaO) 
 
 Fe 2°3 
 
 80 • 80$ 
 
 5.2 
 
 I . 35$ 
 
 
 total 99.98 
 
 This analysis was also made by Dr. W. S. Cox 9 in which he found 
 the analysis to bei- 
 
 Table IV 
 
 Analysis of Missouri Clay (By Dr. W. S. Cox) 
 
 Moisture 
 
 0.60$ 
 
 Wat er 
 
 14.00$ 
 
 Si0 2 
 
 9.30 $ 
 
 a1 2°2 
 
 -73.73$ 
 
 Fe 2°S 
 
 0.57$ 
 
 Na g o 
 
 2.00$ 
 
 k 2 o 
 
 — — 0.52$ 
 
 The clay was then attacked as to its stability to acids and 
 alkalis. A sample was treated in a casserole with the solvent for 
 two days. This was taken to dryness if possible but in the case 
 of sulphuric acid the final step was then heating to dryness with 
 a flame. The residue was taken up in water and filtered and ignited 
 to dryness and weighed. This gave the amount of material which had 
 been decomposed by the solvent. The water soluble portion was then 
 neutralized and made slightly acidic. MH oh and 1TH OH were added to 
 

 
 
 
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13. 
 
 excess and the aluminum hudroxide was filtered off, ignited and 
 weighed. This gave the amount of aluminum which the solvent had 
 dissolved from the sample. This proceedure was followed out with 
 the solvents H 2 S0 4 (cone.), H 2 SQ 4 (dil.), Aqua Regia, NaOh (10 N. ) 
 and KOH (10). 
 
 Table V 
 
 Decomposition of clay by acids and alkali 
 
 20 . 4 c /o 
 
 13.5 # 
 
 16.5 # 
 22.7 # 
 
 20.90 # 
 
 With H o S0/ (cone.) 
 
 " K 2 S0 4 (dil. ) 
 
 M Aqua Regia 
 M NAOH (10 N.) 
 
 " KOH (ION.) 
 
 The amount of alumina which was dissolved from the sample was 
 calculated on the assumption that there was no Iron present. 
 
 Table VI 
 
 Per Cent of Alumina Dissolved from Sample 
 
 With H 2 S0 4 (cone.) 20.4# 
 
 " H 2 S0 4 ( dil.) 13.5# 
 
 H Aqua Regia 4.54# 
 
 NaOH (10 N.) 
 
 KOH ( 10 N.) 
 
 Alumina per cent of total Alumina Content 
 With H 2 S0 4 (conc.) — 25.2# 
 
 " H 2 S0 4 (dil.) — -16.7 # 
 
 '• Aqua Regia — ~ 5.12# 
 
 " NaOh (10 N.) —28.1 # 
 
 KOH (ION.)) —.25.$# 
 
 ——22.7 # 
 20.90# 
 
 ii 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
V. DISCUSSION OF RESULTS 
 
 14 
 
 The aluminous material which is obtained from the counties of 
 Franklinn, Gasconade, and Maries in the State of Missouri has no 
 commercial value for the manufacture of alumina by chemical solvent ;i 
 without the aid of high pressure and high temperature. In order 
 for a mineral to be such it should give up at least fifty per cent 
 
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 of its alumina to a fairly cheap solvent which might be regenerated, 
 and used continously. In the examination of this material I have 
 used the beet and strongest solvents which we have knowledge of, 
 and in no case have satisfactory results been obtained. I find 
 that it was impossible to dissolve more than twenty two per cent 
 of the mineral or was it possible to change more than twenty five 
 per cent of the alumina present into a soluble form. This was 
 sufficient evidence to show that the aluminum was present in the 
 mineral as a silicate or other insoluble form. And this would 
 render that mineral unsuitable for working with chemicals. 
 
 But the value of this ore as an aluminous material does not 
 necessarily lie in its susceptability to solvents. At the pre- 
 sent time the aluminum industry has in use processes which are 
 truly economic ones. They make several requirements which the 
 mineral must fulfill before it can be of use. That is they re- 
 quire that the alumina content must be high, the silica content 
 must be low, the iron and titanium contents must also be low. 
 
 These requirements have so far been fulfilled only by bauxite. 
 
 But here we have an ore which is rich in alumina, which is low in 
 silica, and which has practically no iron and no titanium. This 
 mineral meets the requirements in all respects and should be of 
 value in respect to the "Baeyer Process”. This process uses a 
 

 
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15 . 
 
 a high pressure and heat to break down those bonds which hold the 
 aluminum in the mineral. And that is obviously the only method of 
 attack sonce is so inert to the action of our common solvents. 
 

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16 . 
 
 VI. SUMMARY OF RESULTS 
 
 I. The analysis of the clay given. 
 
 II. The Analysis agrees with that of other investigators. 
 
 5. The alumina content was shown to be higher than was supposed. 
 
 4. The stability of the mineral to acids and alkalis was shown. 
 
 5. The amount of the alumina present which w as susceptible to 
 common solvents was shown. 
 
 6. The aluminum was shown to be present as the silicate rather 
 than the aluminate. 
 
 7. The clay was shown to be undesirable for easy chemical 
 decomposition. 
 
 8. It was shown that the clay was in all probability desirable 
 when applied to such a process as the "Baeyer Process." 
 

 
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 VII BIBLIOGRAPHY 
 
 1. G. A. Roush, Mineral Industry, 29* 7 (1920) 
 
 2. Minet The Production of Aluminum (1905) 
 
 3. Oliver, R. S, 
 
 U. S. Patent 1,301, 394 
 
 Laist, P. 
 
 Chern. Abstr. 13 1907 (1919) 
 
 Freiche, F. F. 
 
 4. Richmond, H. A. U. S. Patent 1,245,383 
 
 Chem. Abstr. 12 253 (1918) 
 
 5. Halvorsen, B. F. U. S. Patent 1,333, 020 
 
 Chem. Abstr. 4__ 1416 (1920) 
 
 6. Patrouilleau, 
 
 L. G. Fr. Patent 
 
 481, 
 
 106 
 
 
 Chem. Abstr. 12 1337 
 
 
 (1918) 
 
 7. Dutt, E.E. . 
 
 U. S. Patent 1,332, 
 
 115 
 
 
 
 Chem. Abstr. 14 1194 
 
 (1920) 
 
 8. Parmelee, 
 
 Cer tidies Department, 
 
 Univ 
 
 . Illinois 
 
 9. Cox, ¥. S. 
 
 Am. Mineralogist 2 
 
 144 
 
 (1917) 
 
 
 3 
 
 154 
 
 (1918)